An objective of orthopedic surgery is to continue developing improved devices and methods that are less invasive to the patient. These efforts include minimizing the incision required to employ surgical instrumentation in the preparation of a bone cavity or socket to receive an implant in, e.g., an acetabular reaming procedure. A way to minimize the incision is to optimize the geometry that the reamer presents to the incision, characterized herein as its “static insertion profile area”. By simplifying the surgical steps required, the reamer design can further lessen total inter-operative time and hence decrease the risks generally associated with longer surgical procedures.
Hollow domed acetabular reamers with hemispherical shapes have previously been disclosed, e.g., PCT/US99/05951 and U.S. Pat. Nos. 5,658,290 and 6,264,647, which are assembled to driving shafts for controlled rotation about a cut axis during the reaming operation. Such prior art acetabular reamers present a circular static insertion profile area (with no straight sides) to the surgical incision, generating a circular dynamic profile area upon rotation of the reamer in the bone socket. A cotyloid reamer is shown in U.S. Pat. No. 6,106,536 having a much different i.e., lop-sided construction compared to the prior acetabular reamers. This cotyloid reamer presents a semi-circular static insertion profile area (i.e., one straight side) to the surgical incision, which is less than the circular dynamic profile area generated upon rotation of the reamer in the bone.
Another objective of orthopedic surgery is to develop instrumentation that is more handily and efficiently used while accurately maintaining a precise cut of the bone socket, in order to minimize inter-operative time. The above-mentioned patent documents also discuss various alternative connections by which their reamers may be assembled to a handle, such assemblies including alignment structures on the reamer and handle allowing controlled rotation of the reamer in the bone socket further to a precision cut.
PCT US02/21310 discloses a reamer that seeks to reduce the static insertion profile area of the reamer to minimize the size of the surgical incision, while providing a precise cut of the desired bone cavity. This reamer employs connections between the reamer and shaft that are designed to perform with a less invasive reamer geometry. These connections function with different handles having a variety of bayonet or other assembly connections, regardless of reamer geometry. This reamer further provides a tool-shaft connection to either a conventional or a less invasive geometry, which allows bone and other organic matter trapped in the reamer, to be removed effectively. The entire contents of the aforesaid PCT/US02/21310 are expressly incorporated by reference herein and relied-upon.
The above-mentioned patent documents have respectively discussed reamers with static insertion geometries that generate dynamic cutting profiles by rotation of the reamer. Generally, there is otherwise no radial expansion or collapsing of the static structure itself.
U.S. Pat. No. 3,702,611 issued to the present inventor discloses a reamer having radially expandable blades that are actuated by cam elements to expand the cutters progressively in response to axial thrust exerted on the drive shaft by the surgeon with the reamer head seated in the acetabulum. A spring is used to contract the cutters when the reaming operation is stopped. The inventor's purpose was to provide radially expandable blades to accurately bottom-out the reamer by using the axial movement (by the surgeon) and radial expansion (of the blades) in combination with one another. However, the cutting structure described by the '611 patent contemplates the use of bladed cutting members rather than a domed apex and/or cutting panels each presenting multiple discrete cutting sites, e.g., of the “cheese grater” type employed by other approaches already discussed above.
Accordingly, it would still be desirable to have a reamer (more particularly an acetabular reamer) that is radially collapsible during passage through a surgical incision then expandable for reaming the bone socket and for collection of debris.
It would be further desirable to provide a hollow dome-shaped reamer having the immediately aforementioned objects, in order to improve accuracy of cut when bottoming-out the reamer in a bone socket, as well as improve the collection of debris.